The invention relates to a circuit breaker for protecting electrical circuits in road vehicles, having a flat, substantially parallelepiped housing, which comprises an insulating material, for a space-saving juxtaposed arrangement. The housing has two substantially parallel top surfaces, in which flat plugs for contacting with a flat-fuse holder protrude out of a housing side wall of the housing. The plugs have flat planes oriented parallel to the two top housing surfaces. The housing side wall penetrated by the flat plugs is formed by a base part that supports the flat plugs, whereas other housing walls of the housing are components of a housing cover that is pushed onto the base part, and enclose functional parts of the breaker. The flat plugs have housing-side ends adjacent to one another that protrude into the housing interior and makes a contact to one another via a bimetal snap disk that is fixed to one of the flat plugs and opens the contact in the event of an overcurrent. The housing cover has a housing opening, which is located in a housing side wall opposite the base part in the assembled state, for a manual release device that lifts the bimetal snap disk out of a position making the contact. The house opening surrounds a bearing shaft for the manual release device, the shaft extending transversely to a passage direction of the manual release device and parallel to the plane of extension of the bimetal snap disk, and being integrally formed onto the housing cover. The manual release device is snapped externally onto the bearing shaft such that, in the snapped-on position, the manual release device acts as a two-armed lever, extending beneath the bimetal snap disk with a release arm that protrudes into the housing interior for selectively acting upon the disk in a contact-opening direction, and protrudes with an actuating arm beyond the housing side wall opposite the base part. These circuit breakers are intended to be used worldwide in motor vehicles equipped with flat fuse sockets, in place of the conventional cut-out fuses according to DIN 72581-3.
It is the object of the invention to permit a simpler method than methods disclosed in DE-A-1099624 for breaking the circuit protected by the automatic circuit breaker arbitrarily, without an overcurrent release, in a circuit breaker of the type mentioned at the outset. For simple, manual circuit breaking, especially in the intended purpose of protecting the electrical circuits of motor vehicles, it is necessary to effectively prevent battery drainage due to creeping currents, e.g., if the vehicle is not used for an extended period of time. This is often the case, for example, from the time of the final inspection of the vehicle until it is delivered to the buyer. In the interim, the vehicle is often transported or stored over long periods.
The manual release device can be designated as a two-armed pivot lever whose release arm is in the inoperative position on the contact side of the bimetal snap disk. In the contact position of the bimetal snap disk, the release arm does not touch the bimetal. Rather, it is held, contactless, in this initial and inoperative position by a spring pressure that is exerted by the bearing shaft of the manual release device onto the lower leg of the release device, as a pivot drive. The special structural feature is that the manual release device acting as a two-armed pivot lever is snapped to the bearing shaft, which is embodied in one piece with the housing cover, by a movable snap connection. This construction is adapted to narrow space conditions, is simple in terms of assembly, and can be realized at a low cost. Finally, a circuit breaker in accordance with the invention can-be mass-produced. The manual release device is lightweight and operates reliably, even under the notoriously narrow conditions of numerous circuit breakers arranged in adjacent rows. When the circuit breaker according to an embodiment of the present invention includes an additional contact separator, it is unequivocally apparent whether a release motion of the release device has effected the desire contact separation: the pressing end of the contact separator protrudes from the breaker housing after the separator is manually released. The actuating arm of the manual release device that protrudes from the housing prevents the contact separator from returning due to pressure exerted on its pressing end, as well as the automatic snap contacting or reclosure of the circuit breaker that may occur afterward, when the bimetal has cooled. Therefore, the subject of the invention can easily be implemented, even in an otherwise unchanged construction of the prior art cited at the outset.